[Sync] Fix namespaces for the sync_sessions component.

components/sync_sessions/revisit/page_revisit_broadcaster_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/sync_sessions/revisit/page_revisit_broadcaster.h"
 
 #include <stdint.h>
 
 #include "components/sync_sessions/revisit/page_visit_observer.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/base/page_transition_types.h"
 
-using sync_sessions::PageVisitObserver;
-
-namespace browser_sync {
+namespace sync_sessions {
 
 class SyncPageRevisitBroadcasterTest : public ::testing::Test {
  protected:
   PageVisitObserver::TransitionType Convert(
       const ui::PageTransition conversionInput) {
     return PageRevisitBroadcaster::ConvertTransitionEnum(conversionInput);
   }
 
   void Check(const PageVisitObserver::TransitionType expected,
              const ui::PageTransition conversionInput) {
@@ skipping 76 matching lines @@
 
 TEST_F(SyncPageRevisitBroadcasterTest, ConvertUnknown) {
   Check(PageVisitObserver::kTransitionUnknown,
         ui::PAGE_TRANSITION_AUTO_SUBFRAME);
   Check(PageVisitObserver::kTransitionUnknown,
         ui::PAGE_TRANSITION_MANUAL_SUBFRAME);
   Check(PageVisitObserver::kTransitionUnknown,
         ui::PAGE_TRANSITION_AUTO_TOPLEVEL);
 }
 
-}  // namespace browser_sync
+}  // namespace sync_sessions